AGC of a hydrothermal system with thyristor controlled phase shifter in the tie-line

This paper presents the analysis of automatic generation control (AGC) of a two-area interconnected hydrothermal system considering a thyristor controlled phase shifter (TCPS) in series with the tie-line. It is possible to stabilize the system frequency and tie-power oscillations by controlling the phase angle of TCPS which is expected to provide a new ancillary service for the future power systems. A control strategy using TCPS is proposed to provide active control of system frequency. Gain settings of the integral controllers without and with TCPS are optimized using integral squared error (ISE) technique following a step load disturbance in either of the areas by minimizing a quadratic performance index. Analysis reveals that a TCPS is quite capable of suppressing the frequency and tie-power oscillations effectively under the occurrence of sudden load changes in any of the areas as compared to that obtained without TCPS